1. Field of the Invention
The present invention relates to a print control apparatus, a print control method, and a medium storing a print control program. More particularly, the present invention relates to a print control apparatus to change the number of nozzles to be used, a print control method, and a medium storing a print control program.
2. Description of the Prior Art
A conventional method of color image printing involves scanning a print head having columnarly arranged nozzles to eject different color inks according to printing data. Printing in this manner produces image lines each consisting of pixels, and the number of nozzles corresponding to individual pixels is previously determined. If one nozzle is assigned to a certain color, each image line is printed with as many nozzles as color inks used. Likewise, if two nozzles are assigned to a certain color, each image line is printed with twice as many nozzles as color inks used. Increasing the number of nozzles constituting one line diminishes banding in full-overlap printing; however, this poses a problem with a decrease in printing speed.
The present invention was completed in view of the foregoing. It is an object of the present invention to provide a print control apparatus to change the number of nozzles to be used for each image line, a print control method, and a medium storing a print control program.
The invention to achieve the above-mentioned object is directed to a print control apparatus which causes a print head to print pixels constituting each image line during its primary scanning, said print head having columnarly arranged nozzles to eject different color inks according to printing data, said print control apparatus comprising an image line judging unit to judge whether or not a prescribed printing condition holds for the image line to be printed and a print control unit to change the number of nozzles to be used for printing each image line depending on whether or not said printing condition holds.
The print control apparatus according to the present invention causes a print head to print pixels constituting each image line during its primary scanning, said print head having columnarly arranged nozzles to eject different color inks according to printing data. While performing printing, the print control apparatus judges whether or not a prescribed printing condition holds for the image line to be printed. Then, the print control unit changes the number of nozzles (overlapping with each other) during the printing of each image line under the printing condition which has been established. In other words, each image line is printed such that the number of nozzles is changed depending on whether or not the printing condition has been established. The printing condition is not specifically restricted; it may be one which is based on the characteristic properties of the print pixels contained in each image line. Alternatively, it may be one which requires the number of nozzles to be changed in specific regions or which specifies specific pixel regions. The mode in which change is made is not specifically restricted; it may be 2-pattern (1 nozzle or 2 nozzles) or 3-pattern (1 nozzle, 2 nozzles, or 3 nozzles).
As explained above, the present invention makes it possible to change the number of nozzles adequately according to the printing condition for each image line at the time of printing.
The print control apparatus of the present invention may be constructed such that the print control unit (which changes the number of nozzles according to the printing condition) causes N nozzles to be used for the printing of an image line for which the printing condition is not established and also causes N+1 or more nozzles to be used for the printing of an image line for which the printing condition holds.
In this case, the print control unit causes N nozzles to be used for the printing of an image line for which the image line judging unit has judged that the printing condition does not hold. Also, the print control unit causes N+1 or more nozzles to be used for the printing of an image line for which the image line judging unit has judged that the printing condition holds. In this way it is possible to present one embodiment in which the number of nozzles is changed.
The printing condition is not specifically restricted as mentioned above. Therefore, it is possible to adopt an embodiment that permits the user to specify the printing condition to change the number of nozzles. In this case the user can conveniently change the number of nozzles at his discretion. Therefore, the print control apparatus of the present invention may be provided with a printing condition specifying unit which specifies the printing condition requiring a change to be made in the number of nozzles to be used for a specific image line.
In this case, the printing condition specifying unit can specify the printing condition (requiring a change to be made in the number of nozzles to be used) for a specific image line. Once the printing condition has been specified, the print control unit changes the number of nozzles to be used in the specific region which has been specified. In this way it is possible for the user to specify the image line for which the number of nozzles should be changed.
For the print control unit to judge whether or not the printing condition holds, the print control apparatus of the present invention may be constructed such that the image line judging unit judges whether or not the image line contains specific print pixels as the print condition.
In this case, the image line judging unit judges whether or not the image line contains specific print pixels as the print condition. In this way it is possible for the user to change the number of nozzles on the basis of print pixels.
Thus the print control apparatus of the present invention may be constructed such that the print control unit causes an image line to be printed with N+1 or more nozzles if the image line judging unit judges that the image line contains print pixels to be formed in a specific dot pattern.
In this case, the image line judging unit judges whether or not the image line contains print pixels to be formed in a specific dot pattern. If judge is so, the print control unit causes the image line to be printed with N+1 or more nozzles.
In this way it is possible to prevent banding by using more nozzles than usual for the printing of an image line which contains print pixels in a dot pattern which is subject to banding.
According to the present invention, the dot pattern in an image line to be printed with N+1 or more nozzles may be one which is formed with dots whose size is approximately equal to the resolution.
In this case, the image line judging unit judges that the print condition holds if an image line to be printed contains print dots formed with dots whose size is approximately equal to the resolution. Thus, the print control unit causes this image line to be printed with N+1 or more nozzles. In this way it is possible to show the dot pattern which is subject to banding.
Alternatively, the print control apparatus of the present invention may be constructed such that the print control unit causes an image line to be printed with N+1 or more nozzles if the image line judging unit judges that the image line contains print pixels to be formed with prescribed inks.
In this case, the image line judging unit judges whether or not the image line contains print pixels to be formed with prescribed inks. And, the print control unit causes the image line to be printed with N+1 or more nozzles if the image line judging unit judges that the image line contains such print pixels.
In this way it is possible to prevent banding by using more nozzles than usual for the printing of an image line which contains print pixels with ink colors which are subject to banding.
According to one embodiment of the present invention, the image line to be printed with N+1 or more nozzles should contain print pixels to be formed with a black ink.
In this case, the image line judging unit judges that the print condition holds if the image line to be printed contains print pixels formed with a black ink. And, the print control unit causes the image line to be printed with N+1 or more nozzles. In this way it is possible to show the ink color which is subject to banding.
In order that an image line is printed effectively with N+1 or more nozzles, the print control apparatus of the present invention may be constructed such that the print control unit causes an image line to be printed with N+1 or more nozzles if the image line is recorded with specific dot species in a ratio higher than specified.
In this case, the print control unit causes the image line to be printed with N+1 or more nozzles if the image line judging unit judges that the image line is recorded with specific dot species in a ratio higher than specified.
In this way it is possible to effectively prevent banding with more nozzles than usual.
In performing printing in prescribed band units, there arises a need to store the image line for which the printing condition holds. Consequently, the print control apparatus of the present invention may have a region storage unit to store the region of the image line for which the printing condition holds.
In this case, the region storage unit stores the image line for which the printing condition holds. In this way it is possible to perform printing in prescribed band units even in the case where the number of nozzles is changed.
In the case where the number of nozzles to be used for printing is changed for each image line, there occurs an instance where nozzles overlap when the mode of print head feeding is changed in accordance with this change. Once nozzles overlap, an image line which has been printed undergoes printing again with other nozzles. Therefore, the print control apparatus of the present invention may be constructed such that the above-mentioned print control unit is provided with the image line print storage unit which stores the image line which has been printed, and the nozzles facing the image line stored in the image line print storage unit are made inoperable (non-eject) at the time of printing.
In this case, the print control unit is provided with the image line print storage unit which stores the image line which has been printed. And, this print control unit make inoperable the nozzles facing the image line stored in the image line print storage unit at the time of printing. In this way it is possible to prevent the overlapping of ink discharge.
On the other hand, it is not necessary to store the completion of printing each time, depending on how the printing condition of the image line is established. Therefore, it is acceptable that storage is made only in the extent to which the completion of printing is required. Thus, the print control apparatus of the present invention may be constructed such that the above-mentioned image line print storage unit has the print finish monitor region which monitors whether or not printing around the image line including the above-mentioned printing pixel has been completed and this print finish monitor region stores the above-mentioned image line.
In this case, the image line print storage unit establishes the print finish monitor region which monitors whether or not printing around the image line including the printing pixel has been completed and the image line print storage unit causes this print finish monitor region to store the above-mentioned image line.
In this way, it is possible to speed up the printing process by establishing the monitor region and executing print monitoring only for the region to be monitored.
The print control apparatus of the present invention may be constructed such that the above-mentioned print finish monitor region is established sufficiently above the image line including the above-mentioned print pixel.
In this case, the print finish monitor region is established sufficiently above the image line including the print pixel for which the printing condition is established.
In this way it is possible to establish the print finish monitor region and exhibit the effective range.
The print control apparatus of the present invention may be constructed such that the above-mentioned print finish monitor region corresponds to the number of nozzles arranged in the above-mentioned nozzle column. This is the typical range to be adopted by the print finish monitor region.
In this case, the print finish monitor region is so established as to correspond to the number of nozzles arranged in the nozzle column.
In this way it is possible to specify the extent in which the print finish monitor region is established.
In the case where the technique to monitor the completion of printing is not employed as mentioned above, it is desirable to print individually the region where the printing condition holds and the region where the printing condition does not hold. Therefore, the print control apparatus of the present invention may be constructed such that the above-mentioned print control unit executes printing in the other image region after it has completed printing for either of the image region formed by the image line containing the above-mentioned print pixel or the image region formed by the other image line.
In this case, the print control unit performs printing for the other image region after completion of printing on either of the image region formed by the image line containing the print image for which the printing condition is established or the image region formed by the other image line.
In this way it is possible to print individually the regions in which the number of nozzles is switched.
There will be an instance where return occurs in the print heat if printing is completed for each region. So, the print control apparatus of the present invention may be constructed such that in the case where return occurs in the above-mentioned nozzle column when printing is performed on the other image region after completing printing for either the image region formed by the image line containing the above-mentioned print pixel or the image region formed by the other image line, the above-mentioned print control unit keeps the above-mentioned print data when scanning is carried out to the state in which no return of the nozzle column occurs and causes the image line to be printed according to the same printing data while rearranging the order of primary scanning so that no return of the nozzle column occurs.
In this case, printing for the other image region is executed by the print control unit after printing has been completed for either of the image region formed by the image line containing the image pixel or the image region formed by the other image line. If return of the nozzle column occurs under this situation, the print control unit keeps printing data while primary scanning is performed to such an extent that no return of the nozzle column occurs and then rearranges the sequence of primary scanning so that no return of the nozzle column occurs and causes the image line to be printed according to the rearranged print data.
In this way it is possible to prevent the return of the nozzle column.
In addition, the technique of printing each pixel of the image line by causing ink to be ejected from the nozzle column while scanning the print head having the nozzle column to eject individual color inks based on the printing data is not necessarily restricted to a tangible entity. It is easily understood that it functions also as its method.
In other words, it is not necessarily restricted to a tangible entity but it is also effective as a method.
In the meantime, such a print control apparatus may exist alone or may be utilized in the form incorporated into a certain apparatus. The concept of the present invention is not restricted to it; however, it includes a variety of embodiments. Therefore, it may take on a form of software or hardware according to circumstances. In the case where the idea of the present invention is embodied in the form of software of the print control apparatus, the present invention covers a recording medium storing such software as a matter of course.
Needless to say, such a recording medium may be a magnetic recording medium or a magneto-optical recording medium or any recording medium which will be developed in the future. The software may be in the form of primary copy or secondary copy. Moreover, the idea of the present invention will be embodied in the form of partly hardware and-partly software. Another possible form is such that a part of software is stored in a recording medium and read in according to need.